Brief Report
Reporting of adverse events in systematic reviews can be improved: survey results

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Abstract

Objective

To assess how information about adverse events is included in systematic reviews.

Study Design and Setting

We included all new Cochrane reviews published in the Cochrane Database of Systematic Reviews (CDSRs) and all new reviews (2003–2004) in the Database of Abstracts of Reviews of Effects (DAREs) in Issue 1 2005 of The Cochrane Library.

Results

More than half of Cochrane (44/78) and DARE (46/79) reviews assessed drug interventions. The rest assessed surgery (Cochrane [12]; DARE [10]), psychosocial, educational, or physiotherapy interventions (22; 23). Seventy-six percent (59/78) of Cochrane reviews mentioned adverse events as an outcome compared with 48% (38/79) of DARE reviews. Most reviews mentioning adverse events were of drug interventions (Cochrane [41/59]; DARE reviews [29/38]). Considering reviews that mentioned adverse events, 95% (56/59) of Cochrane reviews included only randomized trials and 73% (43/59) included an analysis of adverse events. For 10 Cochrane reviews, adverse events had not been reported by the included trials. In contrast, 58% (22/38) of DARE reviews mentioning adverse events included only randomized trials, the rest included both randomized and nonrandomized studies.

Conclusions

Most Cochrane reviews of drug interventions considered adverse events. This was not the case for DARE reviews and for Cochrane reviews of nondrug interventions. This could be improved.

Section snippets

Background

Systematic reviews aim to give an unbiased assessment of the effects of health care interventions. Including information about both beneficial and harmful potential effects of the interventions provides people making clinical, policy, and personal decisions about a treatment with a balanced and realistic account of the likely outcomes.

However, in systematic reviews and randomized trials, the harmful or adverse effects of a particular intervention are often not reported as thoroughly as its

Objectives

The aim of this study was to assess how information about adverse events is currently included in systematic reviews, to identify problematic areas and to quantify the frequency of these problems.

Selection of systematic reviews

A systematic review is defined as a review of a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review. A meta-analysis may, or may not, be used to analyze and summarize the results of the included studies.

We searched CDSRs and included all new Cochrane reviews published in Issue 1 2005 The Cochrane Library. We also searched The Database

Results

Figure 2 shows the number of Cochrane reviews reporting adverse events as an outcome measure by area of disease. Fifty-nine of the 78 (76%) Cochrane reviews provided some mention of adverse events as an outcome measure. It is difficult to fully quantify the amount of information reported on adverse events as it varied considerably across reviews; 11 (19%) Cochrane reviews reported less than five sentences, 21 (36%) reviews reported between one and three paragraphs, 19 (32%) reviews reported

Discussion

This study provides an up-to-date assessment of how information about adverse events is currently included in systematic reviews. We show that currently most Cochrane reviews of drug and surgical interventions consider adverse events to some degree. However, the amount of detailed information varied greatly and in some Cochrane reviews only minimal information was reported on adverse events; 19% of Cochrane reviews reporting adverse events included less than five sentences about adverse events

Acknowledgments

We would like to thank Deirdre Price, Anne Eisinga, and Nandi Siegfried for their help and advice in conducting this study.

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Conflicts of Interest: This study has been carried out as part of the program of methodological research being undertaken at the UK Cochrane Centre, which is funded by the National Health Service Research and Development Programme. The views expressed in this article represent those of the authors and are not necessarily the views or the official policy of The Cochrane Collaboration.

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